Conventionally, diversity receivers equipped with plural receiving branches and capable of improving qualities of signal receptions have been proposed (refer to, for example, patent publication 1). For example, in a conventional diversity receiver, as shown in FIG. 8, a CNR (Carrier to Noise Ratio) meter 1 measures a CNR equivalent to a power ratio of a signal to a noise with respect to radio signals captured by two antennas 2 and 3 respectively; and a receiver 4 performs either a diversity reception or a single reception based upon a measurement result. When the diversity reception is performed, the receiver 4 synthesizes the radio signals received from the two antennas 2 and 3 with each other to output a synthesized signal. When the single reception is carried out, the receiver 4 employs such a radio signal having a higher CNR value within the two antennas 2 and 3, and then, outputs the radio signal derived from the relevant antenna. It should be understood that as the judging elements for judging whether the diversity reception is performed, or the single reception is performed, a fading pitch and the like may be utilized in addition to the CNR. In a diversity reception, although a sufficient reception sensitivity may be obtained, current consumption is large, whereas in a single reception, although current consumption may be small, a sufficient reception sensitivity cannot be obtained. As a result, the diversity reception and the single reception must be properly switched in response on to situations.
Patent Publication 1: JP-A-2004-320528